Generally speaking, it is well recognized that a wide variety of devices for the absorption of gaseous material are available. These devices sometimes find applicability in industry where acid or alkaline gases are absorbed in chemical absorption towers, personal rebreathing systems, and the like. For medical applications, it is common practice to utilize a device for absorbing carbon dioxide.
For this application, a patient is typically connected to an anesthesia breathing circuit. This circuit commonly includes a particulate material which has the capacity to absorb the unwanted gaseous material, i.e., carbon dioxide. While anesthesia breathing circuits are now well known, problems remain.
Naturally, one problem involves the capacity of the particulate material to absorb the carbon dioxide. It is generally desirable to be able to determine the rate of absorption of the carbon dioxide by the particulate material but, in particular, it is critical to be aware of the point of exhaustion of the capacity of the material to absorb the unwanted gas. Obviously, in an anesthesia breathing circuit, it is important to replace the particulate material no later in time than the exhaustion point.
In order to achieve this objective, the person monitoring the anesthesia breathing circuit must have an accurate monitoring technique. It is known, of course, that the particulate material commonly utilized includes an indicating means in the form of a chemically absorbed indicating material such as a color indicator which is pH sensitive so as to change color when the absorbent material no longer has the capacity to absorb carbon dioxide. While this represented a significant advance in the field at its introduction, drawbacks still exist.
As will be appreciated by those skilled in the art, the accuracy of the color indicator is suspect. This follows from the fact that there may be an uneven color change throughout the particulate material or even color reversal particularly if operation of the anesthesia breathing circuit is interrupted even for a brief period of time. Because of factors such as these, there has been a need for an improved technique for visually monitoring the absorbent capacity of the material.
In addition to the foregoing, an anesthesia breathing circuit should also have other visual monitoring features. For instance, it is highly desirable to be able to monitor both inspiration and expiration of a patient who is connected to an anesthesia breathing circuit as well as the existence of an overflow condition. As will be appreciated, any such technique must be highly sensitive to the breathing response of the patient.
Of course, the technique should also provide visual monitoring at a mere glance. It is still further recognized that, particularly in connection with overflow, the exact point of overflow should be variable to accommodate the requirements for any particular patient application. As for other requirements, the anesthesia breathing circuit would be more highly effective with a humidification capability.
The present invention is directed to overcoming one or more of the foregoing problems and achieving one or more of the resulting objects by providing an entirely visually monitored anesthesia breathing circuit.